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<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* 通配符下的样式会对所有的标签生效，但是优先级比较低，几乎是最低 */
        *{
            color: red;
        }
    </style>
</head>
<body>
    <h1>一级标题</h1>
    <h2>二级标题</h2>
    <h3>二级标题</h3>
</body>
</html>